Someone complaining in manner having weight (7)

I believe the answer is:

tonnage

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'weight' is the definition.
(I've seen this before)

I don't understand how the rest of the clue works.

(Other definitions for tonnage that I've seen before include "No agent (anag)" , "Capacity of ship" , "Charge for carrying" , "Measure of cargo space" , "Ship's size or carrying capacity" .)

I've seen this clue in The Telegraph.

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